LeetCode 581. Shortest Unsorted Continuous Subarray

题目

Given an integer array nums, you need to find one continuous subarray that if you only sort this subarray in ascending order, then the whole array will be sorted in ascending order.

Return the shortest such subarray and output its length.

题意

找出最短无排序的子阵列

Example 1:

Input: nums = [2,6,4,8,10,9,15]
Output: 5

Example 2:

Input: nums = [1,2,3,4]
Output: 0

Example 3:

Input: nums = [1]
Output: 0

解题想法

复制排序後的阵列，与原阵列比较元素的不同，从头搜寻，遇到第一个不同的元素，纪录索引值start，从尾搜寻，遇到第一个不同的元素，纪录索引值end，藉由start与end可算出阵列的长度。

Solution

var findUnsortedSubarray = function (nums) {
  let len = nums.length;
  let nums1 = nums.map(x => x).sort((x, y) => x - y);
  let start = 0;
  let end = 0;
  let x = 1;
  let y = 1;
  for (let i = 0; i < len; i++) {
    if (nums1[i] !== nums[i] && x) {
      start = i;
      x = 0;
    }
    if (nums1[len - i - 1] !== nums[len - i - 1] && y) {
      end = len - i - 1;
      y = 0;
    }
  }
  return (start || end) ? end - start + 1 : 0;
};